Watch movement with off-center center wheel and pinion

ABSTRACT

Watch movement with an off-center center wheel driving a third wheel with a friction-coupled auxiliary pinion driving the minute hand which permits setting of the hand while the third wheel is continuously driven, a fourth wheel extending at the same level as said off-center center wheel, resulting in a thinner watch movement structure.

United States Patent 1191 'Zaugg 1 Dec. 18, 1973 WATCH MOVEMENT WITH OFF-CENTER 2,981,055 4/1961 Froidevaux et al 58/59 x CENTER WHEEL A IN 2,903,846 9/l959 Bamat 58/59 2,781,630 2/1957 Bamat 58/59 X Inventori Roland /2g Grenchen, 2,728,187 12/1955 Stamm 58/59 Switzerland 7 l 3] Asslgnee g gzi g i Grenchen Primary Examiner--George H. Miller, Jr.

, Attorney-Richard K. Stevens et al. [22] Filed: Jan. 29, 1973 [21] Appl. No.: 327,428

' [57] ABSTRACT [30] Foreign Application Priority Data Jan. 27, 1972 Switzerland 1213/72 Watch movement with an off-center center wheel 1 driving a third wheel with a friction-coupled auxiliary [52] US. Cl. 58/59 pinion driving the minute hand which permits setting [51] Int. Cl. G04b 33/00 of the hand while the third wheel is continuously [58] Field of Search 58/59 driven, a fourth wheel extending at the same level as said off-center center wheel, resulting in a thinner [56] References Cited watch movement structure.

UNITED STATES PATENTS 3,138,916 6/1964 Beaumann 1. 58/59 4 Claims, 1 Drawing Figure 29 2s 11 2e 32 30 27 31 35 i T 2\o 1i; 1511 l l 7/7,, 0x0 \\\\\\\\\\\\\\\\\\\\\fn\\\\\\\\\\\\\\\\\w & V: I

1 WATCH MOVEMENT WITH OFF-CENTER CENTER WHEEL AND PINION It is known that watch movements with an off-center center wheel, as compared with conventional watch movements where the center'wheel and pinion are actually in the center, have the advantage that with movements of equal diameter, the barrel can be larger since it can extend closer to the axis of the movement. The third wheel and pinion, which are driven by the center wheel, drive the fourth wheel and pinion by means of the third wheel, on thefone hand, and a minute wheel and-pinion, generally disposed on the outer face of the place, by means of a pinion toothing, on the other hand. It is obviously necessary to place a friction coupling between the shaft to which the minute hand is secured and which is integral with a pinion toothing engaging the minute wheel, and one of the wheels of the gear train permanently driven by the barrel, in order to make it possible to set the watch. In most of the known watch movements with an off-center center wheel and pinion this friction coupling is situated between the minute wheel in the center of the movement and the cannon of the cannon-pinion. This centered minute wheel engages the pinion of the third wheel and pinion, which likewise engages the wheel of the center wheel and pinion. Hence, because the centered minute wheel and the off-center center wheel have the same diameter, they rotate at the same speed. For reasons having to do with the mounting, these known calibers were arranged in such a way that the center wheel extended beneath the barrel, i.e., between the inner face of the plate and the barrel, at the same height as the centered minute wheel. The third wheel, on the other hand, extended above the barrel and the fourth wheel especially when the fourth wheel and pinion were disposed in the center of the movement and on above the third wheel, i.e., between that wheel andthe train-wheel bridge.

However, there were great difficulties involved in producing a suitable friction coupling under the conditions described above. There were two reasons for those difficulties for one thing, a relatively high moment of friction, attaining a magnitude on the order of 130 g/mm, had to be ensured; and for another thing, the space available in the center of the movement did not permit lodging resilient elements of a volume sufficient to ensure easily a minimum driving moment attaining the value indicated above.

Recently, friction-coupling systems have been developed which make it possible to obtain quite precise sliding torques without it being necessary to keep within very tight manu-facturing tolerances, and even though these friction-coupling devices do not take up much space. By way of example, a coupling of this type is described in U. S. application Ser. No. 271,131 filed July 12, 1972 of the same applicant. It follows from the date given in that application that this friction coupling could, if necessary be mounted on the shaft of a third wheel and pinion. now then, it was found that by utilizing a friction coupling of this type on the shaft of the third wheel and pinion, it was possible to modify the general arrangement of the caliber adopted up to now in watch movements with an off-center center wheel and pinion, and to obtain an arrangement taking up less space without encountering particular difficulties during mounting.

Thus the object of the present invention is to suggest a novel arrangement of the caliber in a watch move.-

ment with an off-center center wheel and pinion, this novel arrangement ensuring reduced dimensions along with great ease of mounting and a satisfactory solution of the problem of driving the hands by friction, particularly in.the case of movements with automatic winding mechanisms.

To accomplish that, the subject of the present invention is a watch movement with an off-center center wheel and pinion in which the center wheel extends. above the barrel, and the shaft of the third wheel and pinion bears an auxiliary pinion connected to the shaft by a friction coupling, this auxiliary pinion being situated at the level of the centered minute wheel and engaging it, characterized in that the elements of the train are mounted between a train-wheel and a plate, the train-wheel bridge exhibits a recess in its inner face, the third wheel and the fourth wheel pinion are lodged in that recess, and the center wheel and the fourth wheel are situated at the same level.

The accompanying drawing shows in its sole FIG- URE, which is a partial sectional view through the axes of the various wheels and pinions of the gear train, an embodiment of the watch movement according to the invention.

The movement shown in the drawing is in the position corresponding to the mounting, i.e., the plate 1 is at the bottom of the movement, and the train-wheel bridge 2 is at the top. Thesetwo frame elements are connected to one another in a conventional manner which is not shown in the drawing. Plate 1 has at its center a raised and thickened portion 3 into which is driven a pipe 4 which serves as a pivot for a minute wheel and pinion 5 on which is placed the hour-wheel 6. Wheel and pinion 5 and hour-wheel 6 each have coaxial pipes which pass through the center opening of the dial, the one intended to bear the minute-hand at its extremity and the other the hour-hand. it will be noted that wheel and pinion 5 are made up of two parts rigidly fixed to one another and have a pinion toothing 7 which will be caused to engage the usual minute wheel (not shown) and a wheel toothing 8 which is driven in rotation by a train wheel, as will be seen later on. The movement also includes a fourth wheel and pinion 9, the shaft 10 of which is guided by pipe 4, and the pinion 11 of which, as well as the wheel 12, form part of the gear train which transmits the force of the mainspring to the escapement. This train is composed of the barrel 13 which pivots between plate 1 and trainwheel bridge 2 or a special barrel-bar a center wheel and pinion 14, the pinion of which engages the peripheral toothing of the barrel'drurn l3 a third wheel and pinion 15 which will, be described in more detail below, and the wheel 16 of which engages pinion ll of the fourth wheel and pinion; and finally, an escape wheel and pinion 17, the pinion 18' of which is driven by wheel 12 of the fourth wheel and pinion. Wheels and pinions l4, l5 and 17 pivot at boths ends of their shafts in jewels fixed to bridge 2 and to plate 1. As can be seen in the drawing, the wheel 19 of the center wheel and pinion extends between barrel l3 and bridge 2 at the same height as wheel 12 of the fourth wheel and pinion, and wheel 16 of the third wheel and pinion extends above these two last-mentioned wheels in a recess 20 contrived in the inner face of train-wheel bridge 2. This recess is also large enough tohold pinion ll of the fourth wheel and pinion, as'well as the upper end of shaft 14 of the center wheel and pinion.

" ing has four projections, two of which rest against the edges of the two bosses 23, and the other two of which rest in the bottom of groove 25. This ring ensures a friction coupling of regulated torque between shaft 21 and pinion 22. It will be noted in this connection that the moment of friction necessary on the shaft of the third wheel and pinion can be much less than would be the case if the friction coupling were effected between the two parts of wheel and pinion 5, as is usually the case. This maximum torque is, as a matter of fact, limited to about 25 g/mm. When the hands are set, wheel and pinion 5, as well as the minute wheel and hour-wheel 6, are naturally driven in rotation from the winding-stem via the setting-wheel and the clutch-pinion. The result is that pinion 22 turns on shaft 21, which continues to be driven in rotation by the barrel at the usual speed. Because of the low friction torque which is necessary to ensure the driving of the hands under normal conditions i.e., when the winding-stem is in the winding position, the wear on the coupling during setting is much less than if this friction coupling were situated on wheel and pinion 5. In particular, the friction coupling needs no lubrication, which is a considerable advantage.

Although what has been described here is a friction coupling of a special type which has been described in detail in the aforementioned patent application, it is obvious that other friction-coupling systems could likewise be used on the third wheel and pinion. Indeed, the low maximum torque makes it possible to use various embodiments at this location. in particular, the friction coupling described could be replaced by a cup-shaped resilient washer disposed between pinion 22 and the shoulder of shaft 21, pinion 22 itself being axially retained by a ring driven onto the lower end of shaft 21. It is not necessary to keep within extremely precise tolerances, so that this design could be suitable. in another embodiment, it would also be possible to extend the reduced-diameter portion of shaft 21 up to pinion a of the third wheel and pinion and to place on this reduced-diameter portion a coil-spring extending up to pinion 22. in this case, this pinion would likewise be kept in place axially, e.g., by a ring driven onto the lower end of shaft 21.

The arrangement described makes it possible to win a certain amount of height for the automatic winding mechanism. Indeed, as can be seen from the drawing, the stud 26 on which the winding weight (not shown) pivots is integral with a frame element 27 which extends above train-wheel bridge 2. Now then, a booking portion 28 can be contrived in the outer face of bridge 2 around recess 20. As this hooking portion extends very close to the center of the movement, stud 26 can be integral with u thinned portion 29 of frame element .27, while the normally thick portion 30 of that frame element extends over bridge 2 beside hooking portion 28. This thick portion serves to fasten to frame element 27 another frame element 31 which, for example, ensures the pivoting of the wheels and pinions of the reverser actuated by the movements of the automaticwinding weight. The two frame elements 27 and 31 are fixed by one or two screws 32 and as can be seen from the drawing, the head(s) 33 of this screw or these screws can be lodged in one or more openings 34 contrived in bridge 2. Obviously, this arrangement makes it possible to win height equal to the whole thickness of heads 33. The pin 35 serves to fix and adjust frame element 27 on bridge 2. A screw (not shown) will likewise ensure the fastening of element 27 on bridge 2.

With the arrangement described, it is easy to give the toothing of pinion 22 a slightly different diameter than that of pinion 15a. in the movements with an off-center center wheel and pinion up to now, the shaft of the third wheel and pinion included one or two pinion toothings but because of manufacturing considerations, those toothings obviously had to be of the same diameter and the same modulus. With the arrangement described, it is easy to provide different diameters of the two toothings of pinions 15a and 22 mounted on the shaft of the third wheel and pinion the result is therefore greater freedom in the choice of diameters and ratios for the center wheel and pinion and for the centered minute wheel.

Finally, the mounting of the movement can be carried out in a very simple way. The wheels and pinions of the gear train can be placed in the following order, for example escapement, fourth wheel, center wheel, third wheel. The centered minute wheel and pinion will be put in place after the movement has been turned over onto the outer face of the plate, with the minute wheel (not shown) and the hour wheel.

What is claimed is:

1. In a watch movement comprising a train-wheel bridge, a plate, and, between said train-wheel bridge and said plate, a barrel, an off-center center wheel and pinion, a third wheel and pinion, and a fourth wheel and pinion, the arrangement comprising said fourth wheel and pinion being situated at the center of the movement, a centered minute wheel and pinion lodged on theouter face of the plate at the center of the movement coaxially to said fourth wheel and pinion, an auxiliary pinion in meshing engagement with the wheel toothing of said minute wheel and pinion, said auxiliary pinion being mounted on the shaft of said third wheel and pinion, a friction coupling between said auxiliary pinion and said shaft, said third wheel pinion meshing with said off-center center wheel, a recess in the inner. face of said train-wheel bridge, said third wheel and said fourth pinion being lodged in said recess, said offcenter center wheel extending between said barrel and said train-wheel bridge, and said fourth wheel extending at the same level as said off-center center wheel.

2. In the watch movement of claim 1, said third wheel and pinion comprising a pinion integral with said shaft, said integral pinion extending between said third wheel and said auxiliary pinion, adjacent to said third wheel.

3. in the watch movement of claim 1, further comprising an automatic winding device, said device comprising a winding weight rotatably mounted on a fixed stud, said stud being integral with a supporting plate having a thin portion and a thick portion, said stud being made integral with said thin portion, said trainwheel bridge having a hooking portion (28) around said recess, and said thick portion being fixedly connected to the outer face of said train-wheel bridge on the side of said hooking portion.

4. 1n the movement of claim 3, said supporting plate having a frame element of said automatic winding device secured thereto, said element being secured to said supporting plate by at least one screw, said screw having a head, and said head being lodged in an aperture (34) provided through said trainwheel bridge. 

1. In a watch movement comprising a train-wheel bridge, a plate, and, between said train-wheel bridge and said plate, a barrel, an off-center center wheel and pinion, a third wheel and pinion, and a fourth wheel and pinion, the arrangement comprising said fourth wheel and pinion being situated at the center of the movement, a centered minute wheel and pinion lodged on the outer face of the plate at the center of the movement coaxially to said fourth wheel and pinion, an auxiliary pinion in meshing engagement with the wheel toothing of said minute wheel and pinion, said auxiliary pinion being mounted on the shaft of said third wheel and pinion, a friction coupling between said auxiliary pinion and said shaft, said third wheel pinion meshing with said off-center center wheel, a recess in the inner face of said train-wheel bridge, said third wheel and said fourth pinion being lodged in said recess, said off-center center wheel extending between said barrel and said train-wheel bridge, and said fourth wheel extending at the same level as said off-center center wheel.
 2. In the watch movement of claim 1, said third wheel and pinion comprising a pinion integral with said shaft, said integral pinion extending between said third wheel and said auxiliary pinion, adjacent to said third wheel.
 3. In the watch movement of claim 1, further comprising an automatic winding device, said device comprising a winding weight rotatably mounted on a fixed stud, said stud being integral with a supporting plate having a thin portion and a thick portion, said stud being made integral with said thin portion, said train-wheel bridge having a hooking portion (28) around said recess, and said thick portion being fixedly connected to the outer face of said train-wheel bridge on the side of said hooking portion.
 4. In the movement of claim 3, said supporting plate having a frame element of said automatic winding device secured thereto, said element being secured to said supporting plate by at least one screw, said screw having a head, and said head being lodged in an aperture (34) provided through said trainwheel bridge. 